Those questions are being tested like never before in Iraq, with a general Sunni Arab uprising comprised of jihadis, former Iraqi army officers and soldiers, and major tribal confederations, taking vast stretches of territory. And while US Secretary of State John Kerry was in Iraq's semi-autonomous Kurdistan urging national reconciliation today, the Kurds have already carved out more territory for themselves and may see an opportunity to strike out alone.

"We are facing a new reality and a new Iraq,” Kurdish Regional Government President Massoud Barzani told Mr. Kerry today.

The oil-rich city of Kirkuk, which Kurdish forces occupied without firing a shot after the Iraqi army fled in fear of a Sunni rebel assault earlier this month, is shaping up to be part of that new reality.

Since 1991, when NATO imposed a no-fly zone in northern Iraq, the Kurds have carved out a semi-autonomous homeland. The region's de facto independence from Baghdad has only grown since the US-led invasion of Iraq in 2003: The regional government collects its own taxes, runs its own military and police force, and exports its own oil, infuriating Baghdad. Earlier this week Israel announced it was buying about $100 million of crude oil from the Kurds.

In the political order the US helped create in Iraq, independence-minded Kurds are also kingmakers in national parliamentary politics. Representing about 20 percent of Iraq's population, Kurdish politicians can swing a coalition in a fractured parliament. Iraq's parliament-appointed President is Kurdish politician Jalal Talabani, just one of the concessions that brought to power the current Prime Minister Nouri al-Maliki, whose Shiite bloc won a plurality in April's elections.

Kurds in Iraq have long dreamed of retaking Kirkuk and making it their national capital. Their peshmerga fighters have stood tall as the Iraqi army has crumbled. These forces have coordinated aid and protection for refugees fleeing Mosul and other cities and towns that have fallen.

“It is impossible for gunmen to take Kirkuk because the peshmerga protect it,” insists Dler Samad Swani, a local official.

More trouble for Baghdad

But Kurdish gains in Iraq at the expense of Baghdad could ripple outward, particularly at a time when borders drawn up a century ago by European powers are fraying rapidly.

Kurdish minorities are often at odds with governments in the region. Iran, a staunch backer of Iraqi Prime Minister Nouri al-Maliki, has a restive Kurdish population and is alarmed at the threat to the stability of Iraq, a reliable ally since 2003.

A similar dynamic is at play in neighboring Syria, where a bloody civil war still rages and has fed the extremism of the Islamic State of Iraq and the Levant (ISIS) and other jihadi groups. Syria has a substantial Kurdish minority that would be happy to carve out a chunk of the country for itself, as does Turkey, which borders Iraqi Kurdistan. Turkish jets and artillery have hit Kurdish militants taking sanctuary over the border in years past.

Looming over all of this is the rise of ISIS – a jihadi group that is ultimately hostile to every ruling elite in the region. That is what puts the Kurds in such a strong position, as regional and international powers weigh their options for stabilizing Iraq and keeping it intact. The Kurds are simultaneously a threat to a unitary Iraq in its modern form – and perhaps the greatest hope to preserving it.

“Anything that is a challenge, like Kirkuk, ISIS will avoid,” says Kirkuk Deputy Gov. Rokaan Siad. “Their goal is Baghdad and the overthrow of Maliki’s regime.”

Living in interesting times

Mr. Siad, an ethnic Arab, is one of many officials struggling with the shifting fronts in this mosaic region of religious and ethnic identities.

Between the stress of securing his family – his wife and children are in hiding in a nearby ISIS-held area – and a flurry of meetings to keep services such as water and electricity running in Kirkuk, the deputy governor says he hasn’t slept in days.

Security is the top priority of local authorities and the main demand of jumpy residents who fear that ISIS, in the long term, may prove a bigger problem than sour ties with Baghdad.

“ISIS is a scary neighbor to have,” says Can, a hairdresser in Kirkuk who declined to give her full name.

That fact is dawning on more than the residents of northern Iraq. Hezbollah, the Lebanese Shiite militia and political party, has said it is considering moving some of its own fighters into Iraq to protect Shiite shrines and shore up Mr. Maliki. That could be a setback for Syrian dictator Bashar al-Assad, who has increasingly relied on Hezbollah fighters to help him drive out rebels.

Saudi Arabia is watching matters closely. Saudi policy has long been to weaken Shiite-dominated Iraq, and rich Saudi donors were major supporters of Sunni Arab tribes fighting US forces and the central government during the US-led war here. Maliki has accused Saudi Arabia of fomenting the current unrest.

But while Saudi rulers might like the Maliki government to fall, they also fear the growing territorial reach of ISIS whose ultimate goal, much like Al Qaeda’s, would be the overthrow of the Saudi monarchy. Saudi Arabia has named ISIS an official terrorist organization and increased penalties for anyone caught supporting or fighting with it.

Threats to Kurds

Kurds, too, face the possibility that ISIS – assumed to be maintaining its focus on other fronts – could eventually target the Kurds.

“The Kurds see Daash [the Arabic acronym for ISIS] as a threat not just to Baghdad but to the whole region,” says Kurdish parliamentarian Tania Talat. “ISIS calls the Kurds the deferred enemy.”

Shwan Muhanad, editor in chief of Kurdish-language website Speemedia, agrees. “Daash’s main goal is the fall of Maliki. When they achieve this, the Kurds will be the next target.”

That concern may lead to greater cooperation between the Kurdish Regional Government and central authorities in Baghdad, provided the Kurds don't decide to go it alone. “Iraq is obviously falling apart,” President Barzani told CNN yesterday. “We did not cause the collapse of Iraq. It is others who did. And we cannot remain hostages for the unknown.”

The Iraqi Kurds’ key demands of Baghdad to date include a greater role in decision making, a larger share in oil revenues, weapons and funding for the peshmerga, and the implementation of an article in the Iraqi Constitution that would expand the territory under Kurdish rule. Maliki’s government has been steadfastly opposed to those demands, and will probably remain so. Passions are running high among Maliki's Shiite Arab constituents, with Shiite militias reforming and clerics calling the community to arms, and giving away Iraqi territory and oil revenue would not prove popular among them.

But absent those concessions, the most powerful military force in Iraq is unlikely to help Baghdad.

“The Kurdish leadership will not take any decisions to fight against Daash directly without guarantees from the US, al-Maliki, and Iran,” says Mr. Muhanad.

Staff writer Dan Murphy contributed to this report.

(A version of this story ran in the June 30 issue of the Christian Science Monitor weekly magazine).